GB840306A - Improvements in direct current power supply units - Google Patents

Abstract

840,306. A.C. generators. GENERAL MOTORS CORPORATION. Dec. 23,1958 [Dec. 26, 1957], No. 41459/58. Class 35. [Also in Group XXXVI] In an A.C. generator feeding a D.C. load through rectifiers for motor vehicles, the rectifiers are mounted in heat-transfer relationship with the alternator end cover. In an air-cooled form shown in Figs. 1 and 2, in which the alternator may be of any type but as shown is of single or polyphase type with a rotating field member energized through slip-rings 36, 38, and brushes 40, the rectifiers are arranged as plugs 48, 84 in holes in radial webs in the end cover 18. These rectifiers are of conventional silicon junction type (see Group XXXVI) and the threaded casing parts and insulated terminals 54, 104 provide the two terminals of the rectifiers. In the three-phase form shown, three rectifiers 48 are secured in webs 66 in the end cover, these webs having heat-dissipating fins 70. An insulated sub-frame 72, similarly provided with webs 82 having fins 83 carries a further three rectifier plugs 84 of opposite polarity to plugs 48. The sub-frame 72 is connected to the D.C. output terminal 76 and the end cover 18 provides the earth terminal, the stator windings 22 of the alternator being connected to the insulated rectifier terminals 54, 104 to provide a three-phase, full-wave bridge. The end cover 18 is thermally insulated from the stator by a spacer 19. In an oil-cooled modification, Fig. 6, the rotor has interdigitated poles 112, 114 alternately polarized by a fixed field coil 130. The rectifier plugs 132, 134 are embedded in the end cover 89, plugs 134 being threaded directly into the earthed end cover, while plugs 132 are insulated from it by insulation 142. Metal strips 144 provide cooling fins and also terminal lugs for the rectifiers 132. The rectifiers are connected in a three-phase bridge as before. Cooling oil from a pump 170 and cooler 171 is fed into rectifier cooling chamber 156 at pipe 160 connected by an arcuate duct 161 to the bottom of the chamber 156. Back-syphoning is prevented by a bleed hole 161a. Oil also passes by ducts 162, 164, 165 to the air-gap 166 to cool the alternator parts, and by a duct 174 to lubricate rotor bearing surfaces 123, 124 before draining at 173 to sump 172. This sump may be the flywheel or transmission housing of the motor vehicle. Instead of being screwed into the end cover, the rectifier plugs may be pressfitted into suitable bores, or the rectifier elements may be secured directly into recesses in the end cover by turning the edges over so as to secure an insulated terminal portion.